In a manufacturing process for a circuit board having a conductive pattern formed thereon, it is necessary to inspect the presence of a defect, such as disconnection or short circuit, in the conductive pattern formed on the circuit board.
Heretofore, as a technique for inspecting a conductive pattern, there has been known a contact (pin contact) technique which comprises binging a plurality of pins into contact with first and second opposite ends of a conductive pattern, supplying an electric signal from the pins in contact with the first end to the conductive pattern, and receiving the electric signal from the pins in contact with the second end, so as to inspect continuity or other quality factor of the conductive pattern, as disclosed, for example, in the following Patent Publication 1. In this technique, a certain current serving as the electric signal is supplied to the conductive pattern from a plurality of metal pin probes which are put on respective end terminals of the conductive pattern.
The pin contact technique based on the pin probe set in direct contact with the end terminals has an advantage of being able to achieve a high S/N ratio.
However, the direct contact of the pins is likely to cause a problem about damages in a conductive pattern, particularly in a circuit wiring pattern formed on a glass board for a liquid-crystal panel, which has a small pattern thickness and a low fixing strength relative to the board.
Further, in an inspection of an electronic component, such as a liquid-crystal display panel for portable phones, where the wiring pitch of a conductive pattern becomes finer and finer, a number of pin probes having a fine pitch have to be prepared by consuming a great deal of time and cost.
In addition, the pin probe set has to be newly prepared for each circuit board (inspection target) having a conductive pattern different in configuration. This leads to increase in inspection cost, resulting in major hindrance to cost reduction of electronic components.
Particularly, as described in detail later, a conductive pattern for use in a liquid-crystal display panel includes first and second comb-shaped conductive patterns each having a plurality of terminal portions arranged substantially parallel to each other and a base portion connecting respective anchor ends of the terminal portions together, wherein the terminal portions of the first comb-shaped conductive pattern are alternately arranged with respect to the terminal portions of the second comb-shaped conductive pattern. The circuit board also includes another conductive pattern formed thereon to surround the first and second comb-shaped conductive patterns. That is, each of the conductive patterns is in a short-circuited state. Thus, any appropriate inspection apparatus for this type of circuit pattern has not been put into practical use.                Patent Publication 1: Japanese Patent Laid-Open Publication No. 62-269075        
There is a strong need for providing a circuit pattern inspection technique for a liquid-crystal display panel having a low fixing force between a circuit pattern and a board, and achieving an inspection apparatus free from causing damages in the pattern.